Aggregate dividends paid during the period for each share of common stock outstanding.

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-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 04

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The day, month, and year (YYYY-MM-DD) that the dividend declared as of or prior to the financial reporting date will be paid in the subsequent period.

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The aggregate amount of dividends declared, but not paid, as of the financial reporting date.

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-Name Statement of Financial Accounting Standard (FAS)

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The per share amount of a dividend declared, but not paid, as of the financial reporting date.

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The date as of when a holder must own the stock to be entitled to the dividend. The ex-dividend date is generally 3 days before the record date.

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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The cash outflow from the distribution of an entity's earnings in the form of dividends to common shareholders.

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Dividends - Additional Information (Detail) (USD $)	3 Months Ended				9 Months Ended		1 Months Ended
Dividends - Additional Information (Detail) (USD $)	Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2011	Sep. 30, 2010	Sep. 30, 2011	Sep. 30, 2010	Nov. 04, 2011 Dividend Declared
Dividends Payable [Line Items]
Cash dividend paid, per share amount	$ 0.11	$ 0.11	$ 0.11	$ 0.11	$ 0.33	$ 0.32
Dividends paid on common stock					$ (23,361,000)	$ (24,513,000)
Cash dividend declared per share amount							$ 0.11
Cash dividend payable date							Dec. 15, 2011
Dividend payable, date of record for common stock holders							Dec. 01, 2011
Expected dividend payment amount							$ 7,800,000